This invention relates to molluscicides, and more particularly to a combination of molluscicides which act in a synergistic manner to effectively control the growth and life of mollusks.
Many mollusks, including snails and slugs, terrestrial as well as aquatic cause serious economic and health problems in many parts of the world. Snails which are members of a large class of gastropod mullusks, including most forms having a univalve shell or having no shell can be quite injurious to vegetation as they destroy many varieties of beneficial agricultural plants. Even more harmful is the role that they play in the life cycle of many tropical and semitropical diseases. Millions of people and countless animals in many parts of the world are afflicted with these diseases. Snails play a significant role in the growth cycle of the parasite involved in these diseases. With snails, the parasite's larval stage develops and emerges. The latter enters warm-blooded animals where it matures into worms. The worms in turn lay eggs which are carried to vital organs in the animal body by the blood stream. Lastly, the eggs find their way back to the snails through water supplies and the like and the cycle begins once again. Thus, a single snail can be the ancestor of many millions of new snails per year.
For example, snails of the genre Oncomelania, Australorbis and Bulinus are schistosome intermediate hosts. Likewise, snails of the genre Lymnaea are intermediate hosts for the liver flukeworm. Snails of these types particularly cause debilitating human problems. Specifically, bilharziasis has long been endemic in various parts of the world, and is even on the increase.
While various methods of combating bilharziasis and other diseases of this type have been suggested, the destruction of the intermediate snail hosts by toxic chemicals appear to be the most rapid and effective means for reducing transmission of many tropical and semitropical diseases.
However, many chemicals useful in combating mollusks (molluscicides) such as snails have certain disadvantages. In some cases they are difficult to formulate and in certain types of habitats, the available formulations cannot be effectively dispersed. In other instances, the chemical itself is irritating and potentially dangerous to the handler, or it is required to be used at relatively high dosages. In still other instances, it is prematurely absorbed by the soil or other organic materials. Also, some molluscicides currently on the market are ineffective at a high pH, are corrosive to equipment, or their activity is reduced by bright sunlight. Lastly, some molluscicides, while sufficiently active, are inactivated at a low pH and/or do not kill snail eggs.
There is, therefore, the need to provide an effective molluscicide which will not have these side effects, but will directly and surely kill snail eggs upon the treatment of the snails or their habitat.